xkcd time twitter profile image changer (in action - https://twitter.com/skakri)

gistfile1.py

import Image
import ImageChops
from twython import Twython

with open('current.txt', 'r+') as f:
    index = int(f.read().strip())
    new_index = index + 1
    f.seek(0)
    f.truncate(0)
    f.write(str(new_index))
    f.close()

with open('sequence.txt') as f:
    lines = f.readlines()
    lines = map(lambda s: s.strip(), lines)
    f.close()

    file_one, file_two = lines[index:index + 2]

    im1 = Image.open('images/' + file_one)
    im2 = Image.open('images/' + file_two)

    diff = ImageChops.difference(im2, im1)
    left, top, right, bottom = diff.getbbox()

    width = right - left
    height = bottom - top

    side = max(width, height)
    halfside = side / 2

    hcenter = left + width / 2
    vcenter = top + height / 2

    cropped = im2.crop((hcenter - halfside, vcenter - halfside, hcenter + halfside, vcenter + halfside))
    cropped.save('current.jpg')

    twitter = Twython(APP_KEY, APP_SECRET, OAUTH_TOKEN, OAUTH_TOKEN_SECRET)

    avatar = open('current.jpg', 'rb')
    twitter.update_profile_image(image=avatar)